Malaria Vaccine
7.11.2021
According to CDC, malaria is a critical, potentially fatal disease caused by the parasite, Plasmodium falciparum- which feeds on human blood. Symptoms of malaria are typically similar to the flu with high fevers, chills, and headache. Although there are other plasmodium species that cause malaria, P. falciparum causes symptoms that may most likely result in severe cases and possibly death, if not promptly treated. Generally, illness and death from malaria can usually be prevented.
About 2,000 malaria cases are diagnosed in the United States annually, majority which are travellers and immigrants returning from parts of the world where malaria transmission occurs, particularly sub-Saharan Africa and South Asia. Worldwide, millions of malaria cases occur clinically causing hundreds of thousands of deaths. Malaria transmission occurs when people are bitten by infective female Anopheles mosquitoes- the only mosquitoes that transmit malaria, and they must have been infected by a P. falciparum through a previous blood meal from an infected person. Malaria can also be transmitted through blood transfusion, organ transplant or the shared use of needles or syringes contaminated with blood because the malaria parasite is found in red blood cells of an infected person. Malaria may also be transmitted from a mother to her unborn infant before or during delivery, known as congenital malaria. Malaria is not spread from person to person, and it cannot be sexually transmitted.
Scientists have been working hard to find a vaccine for malaria, however, a completely effective vaccine is not yet available. Currently, there are several vaccines under development- these vaccine candidates target the blood-stage of the parasite’s life cycle but that has not been sufficient. Consequently, several potential vaccines targeting the pre-erythrocytic stage are being developed.
So far, R21/Matrix-M, with 77% efficacy shown in clinical trials is the most effective malaria vaccine. It meets the World Health Organization’s goal of a malaria vaccine with a requirement of at least 75% efficacy. The vaccine was developed following a collaboration of various institutions including Oxford University, Kenya Medical Research Institute, London Hygiene and Tropical Medicine, Serum Institute of India amongst others. Further clinical trials are needed to approve the vaccine, which has an expected annual production of 200million doses.
More so, RTS,S- developed by PATH Malaria Vaccine Initiative (MVP) and GlaxoSmithKline (GSK), and supported by Bill and Melinda Gates Foundation is a recent recombinant vaccine which comprises of the P. falciparum circumsporozoite protein (CSP) from the pre-erythrocytic stage. The CSP antigen stimulates the production of antibodies capable of preventing the infection of blood cells as well as destroying already infected cells. The vaccine is commercially traded as Mosquirix, and requires four injections.
In July of 2015, Mosquirix was positively appraised by the European Medicines Agency (EMA) on the proposal for the vaccine to be used in children aged 6 weeks to 17 months outside the European Union. Subsequently, a pilot project for vaccination was launched in 2019 for children in Malawi, Ghana and Kenya. The vaccine was then endorsed by the World Health Organization in October 2021.